32
RGU-10 MT
Instruction Manual
8.- RS-485 COMMUNICATIONS
8�1�- MODBUS CONNECTION
The RS-485 connection must be wired using twisted pair cable with a mesh shield (minimum 3 wires),
with a maximum distance of 1200 meters between the
RGU-10C MT
and the master unit. A maximum
of 32 slave devices can be connected to this bus.
8�2�- MODBUS PROTOCOL
The
RGU-10C MT
model communicates using the MODBUS RTU© protocol (query/reply polling).
Within the Modbus protocol, RTU (Remote Terminal Unit) mode is used; each 8-bit byte in a message
contains two 4-bit hexadecimal characters. The format for each byte in RTU mode
Code:
8 binary bits, hexadecimal 0-9, A-F
2 hexadecimal characters contained in each 8-bit field of the message.
Bits per byte:
8 data bits
Check-Error:
CRC (Cyclical Redundancy Check) type
Modbus functions used:
Function 0x03:
Read
Function 0x06:
Write
8�2�1�- READING EXAMPLE
Query:
Peripheral
Nº
Function
Initial
register
Nº of registers
CRC
0A
03
0000
000A
7176
Peripheral number:
0A, 10 in decimal
Read function:
03
Register where you want the reading to start:
00 00
Number of registers to read:
00 0A , 10 in decimal
CRC character:
71 76
Response:
Peripheral
Nº
Function
Nº of
bytes
Reading
CRC
0A
03
14
00 0A 00 02 00 00 00 32 00 00 00
01 00 00 00 01 00 14 00 00
7EC9
Peripheral number:
0A, 10 in decimal
Read function:
03
Number of bytes received:
14, 20 in decimal
Registers:
00 0A: Address 0000: Peripheral number (10)
00 02:
Address
0001: Communication baud rate (2- 9600 bauds)
00 00: Address 0001: Parity type (0 - None)
Summary of Contents for RGU-10 MT
Page 1: ...INSTRUCTION MANUAL Electronic earth leakage protection relay RGU 10 MT Serie M98228501 03 21A...
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